Mass Movements
Mass Movement is defined as the downward movement of surface materials caused by wind erosion. (True or False)
False
(This statement is incorrect because gravity plays a major role in mass movement. While wind erosion can contribute to some downhill movement of loose materials, it's not the primary driving force. )
A landslide is defined as the upward movement of water through soil and rock layers. (True or False)
False
(While water movement can be a factor that triggers landslides, the actual landslide itself refers to the downward movement of earth materials. )
Ground subsidence is the gradual setting or sudden sinking of the Earth’s surface. (True or False)
True
One way to prevent destruction due to landslides is to avoid constructions on locations of previous landslide occurrences. (True or False)
True
Being cautious of any Sudden Changes of the Amount of Water Flow is important before a landslide occurs.
False
Why:
This act must be done during a landslide.
What are the 2 Classifications of Mass movements?
Downslope and Vertical Movement
Involve the forward rotation and movement of a mass of rock, earth or debris out of a slope
Topple
What are the 2 causes of subsidence?
Mines and Geosciences Bureau
When should Staying Away from Were Landslides have Occurred be done?
After the Landslide
Refers to the human activities including pollution, land conversion, urbanization, and mining
Anthropogenic Effect
What does the Pink Legend of a Landslide and Susceptibility Map mean?
Possible landslide debris accumulation zone
What are the 4 types of rocks that contribute to the possibility of sinkholes to happen
Limestone
Carbonate Rock
Salt Beds
Rocks that can naturally be dissolved
What is the first strategy for preventing and mitigating mass movements?
The use of susceptibility maps provided by MGB
What are the 3 things to look out for before a landslide occurs?
Look for Warning Signs, Preventing Landslides, Household Precautions
Why is the Philippines prone to geologic hazards?
Due to its location in the tropics and the presence of communities in the bases of mountains and hills.
What are the 4 agencies that aid the government and the people in preparing for a disaster?
PAGASA, MMDA, DOST (PHIVOLCS), DENR, El Observatorio de Manila (Manila Observatory)
What was the date when a major subsidence incident occurred in the Rockrimmon area of Colorado Springs?
April 1979
Name at least 3 of the Engineering Solutions needed to be implemented to prevent and mitigate mass movements
Slope Reinforcement, Slope Modification, Water Management, Rockfall Protection, Ground Anchoring
Name at least 2 Household Precautions needed to be done before a landslide occurs
You're inspecting a long crack that recently appeared in the foundation of your house. The crack is thin and runs along a straight line for several feet. Over the past few years, you haven't noticed any significant changes in the foundation or any issues with doors or windows getting stuck. What type of phenomenon does the scenario involve? Explain.
Slow Phenomena
Why:
The thin, straight crack and the lack of past issues suggest a gradual process, not a sudden event that would cause a more dramatic crack or immediate structural problems.
You're leading a nature hike through a forested area with a well-maintained trail. The ground is slightly damp from a light drizzle earlier that morning. As you round a bend in the trail, you notice a fresh patch of exposed soil on the slope beside the path, about the size of a large car. There are a few small rocks scattered around the exposed area, and a couple of young trees are leaning slightly at the edges. What is the estimated landslide size?
Small
Why:
The exposed soil patch is only the size of a large car, indicating a small amount of displaced material. The fact that the trail is well-maintained suggests the slope is generally stable, and a large landslide is unlikely, and the light drizzle wouldn't be enough to trigger a major landslide event.
While hiking through a dry riverbed, you notice a large, circular depression in the ground ahead. The depression is about the width of a school bus and several feet deep. The ground around the depression appears cracked in a spiderweb pattern, and there are no signs of water erosion within the depression itself. Is this more likely classified as ground subsidence or a sinkhole?
Sinkhole
Why:
Sinkholes are typically characterized by a circular depression in the ground, while subsidence can cause depressions with various shapes. The lack of water erosion within the depression further indicates it's not a result of ongoing surface water flow, which wouldn't necessarily be the case with subsidence.
You're a civil engineer overseeing the construction of a new highway through a mountainous region. Two potential routes have been identified:
Route A: A shorter route requiring extensive blasting through a series of steep slopes composed of loose rock and scree. Geological surveys indicate a high risk of landslides in this area.
Route B: A longer route that follows a valley floor with gentler slopes and more stable underlying geology. Construction costs would be higher due to the longer distance.
Considering both construction costs and public safety, which route is the most advisable option? Explain.
Route B
Why:
Route A's high risk of landslides due to loose rock and scree poses a significant threat to public safety during and after construction. Even if construction manages to avoid triggering landslides initially, the unstable slopes could pose a risk to the highway itself in the future. While Route B has higher construction costs, these are likely outweighed by the long-term benefits of a safer and more stable route.
You're camping with friends in a remote wilderness area. After a night of heavy rain, you wake up to a roaring sound echoing through the valley. Looking out from your tent, you see a massive mudflow surging down a distant hillside, tearing through trees and rocks in its path. The flow seems to be heading towards the general direction of your campsite, although it's still a considerable distance away. However, the sound is getting progressively louder, and the ground beneath your feet feels like it's vibrating slightly. What's the MOST IMPORTANT action you should take immediately to stay out of the path of the debris flow?
Move to higher grounds in the direction away from the flow as quickly and safely as possible.
Why:
By running near the highest ground and away from the path of the flow, you're minimizing the risk of being caught in its path or buried by debris.